With the development of science and technology, fuel vehicles are being replaced by environment friendly and energy saving electric vehicles. However, the popularization of the electric vehicles encounters some problems, among which high driving mileage and fast charging technology has become major problems in the promotion of electric vehicles.
Currently, large-capacity batteries are used in most electric vehicles. However, although these batteries may enhance the endurance time of the electric vehicle, they make a charging time too long. Although a specialized DC (direct current) charging station may charge a battery quickly, problems such as high cost and large occupied area make the popularity of such an infrastructure encounter a certain difficulty. Moreover, because of a limited space of another electric vehicle, an in-vehicle charger may not satisfy the requirement of a charging power due to the limitation of its volume.
A charging solution currently used in the market comprises the following solutions.
Solution (1)
As shown in FIGS. 1-2, an in-vehicle charging or discharging device in this solution mainly includes a three-phase power transformer 1′, a three-phase bridge circuit 2′ consisting of six thyristor elements, a constant-voltage control device AUR, and a constant-current control device ACR. However, this solution causes a serious waste of space and cost.
Solution (2)
As shown in FIG. 3, an in-vehicle charging or discharging device in this solution includes two charging sockets 15′, 16′ to adapt to the single-phase/three-phase charging, which increases the cost. A motor driving loop includes a filtering module consisting of an inductor L1′ and a capacitor C1′. When a motor is driven, a loss of a three-phase current is generated when it flows through the filtering module, which causes a waste of an electric quantity of a battery. With this solution, during the charging or discharging operation, an inverter 13′ rectifies/inverts an AC (alternating current) electricity, and the voltage after the rectifying/inverting may not be adjusted, such that an operation voltage range of the battery is narrow.
Therefore, most AC charging technologies currently used in the market are a single-phase charging technology, which has disadvantages including low charging power, long charging time, large hardware volume, single function, restriction by voltage levels of different regional grids, etc.
In addition, the electric vehicle only supplies the electric energy stored in the power battery to the motor so that the motor drive another electric vehicle to move. While the another electric vehicle is in OK gear, after the another electric vehicle collects the gear signal and the throttle signal, the motor driving controller inverts DC supplied by the battery into AC and outputs the AC to the motor. Then the motor rotates to drive the another electric vehicle.
With the development of science and technology, fuel vehicles are being replaced by environment friendly and energy saving electric vehicles. However, the popularization of the electric vehicles encounters some problems. Due to the effect of the road condition or the users' habits, the driving distance of the another electric vehicle which is calculated by the battery manager may have certain errors. Therefore, it is possible that the electric quantity of the power battery is insufficient or even has been exhausted before reaching the destination, which may make the another electric vehicle unable to move, thus involving the user in trouble.